Re: [PATCH 1/2] jbd2: check bh->b_data for NULL injbd2_journal_get_descriptor_buffer before memset()

From: Theodore Ts'o
Date: Mon Jun 03 2013 - 11:33:32 EST

On Mon, Jun 03, 2013 at 01:00:15PM +0300, Ruslan Bilovol wrote:
> The memset() doesn't perform any NULL-pointer checking
> before dereferencing passed pointer so this should be
> checked before calling it.

I can see that __getblk() can return NULL if there is a memory
allocation failure (and is defined to do so), so checking to make sure
bh is not NULL is a good thing to do.

Have you actually seen a case where bh is non-NULL, but bh->b_data is
NULL? If not, it might be better to do something like this:

> bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
if (!bh)
return NULL;

- Ted
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